Helen Fryer

Helen Fryer is credited as the author of The Esperanto Teacher, a beginner-friendly manual for learning Esperanto that circulated in the early 20th century. The work is old enough to appear in public-domain collections, which suggests it played a small but lasting role in the spread of the language to English-speaking learners.

Reliable biographical details about her life are scarce in the sources I could confirm. Because of that, it is safest to remember her primarily through her published work rather than through a fuller personal biography.